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Cognitive Cardiovascular Experiment (Cardiocog-2) - 05.13.15

Science Objectives for EveryoneThe Cardiocog-2 experiment studies the impacts of microgravity (weightlessness) on the cardiovascular system and the respiratory system. This investigation will examine the stress as well as the cognitive and physiological reactions of crewmembers during long-duration space missions.

Science Results for Everyone
This study recorded cardiovascular data from six astronauts on long-duration flights on the space station, adding to a previous study, Cardiog-1. It is confirmed that heart rate and blood pressure do not change significantly on short space flights, but that long-term flights seem to slightly reduce blood pressure. One interesting and unexpected result was that nervous system feedback of blood pressure linked to controlling heart rate appeared to slow significantly in space. The causes are unclear and need further investigation. Post-flight symptoms strongly supported use of effective exercise countermeasures in adaptation to prolonged missions. Individual performance on countermeasures should be shared among scientists to improve the data from these studies.

The following content was provided by Andre E. Aubert, and is maintained in a database by the ISS Program Science Office.
Information provided courtesy of the Erasmus Experiment Archive.

Cardiocog-2 will determine the impact of weightlessness on the cardiovascular system and respiratory system and the cognitive reactions of crewmembers.

The results of this study will be used to develop additional countermeasures that will continue to keep crewmembers healthy during long-duration space exploration.

Description
On four occasions over the course of the mission the astronaut will undertake a half-hour protocol of normal and controlled breathing together with a stress test. Cardiac activity, respiration and blood pressure will be measured continuously during this activity using the Cardioscience equipment already aboard the International Space Station (ISS). This will be compared against additional ground tests where ECG (electrocardiogram), blood pressure, respiration and ultrasound measurements are taken. This is a continuation of the previous Cardiocog experiment and is proposed to continue with three additional long-term crewmembers. This experiment will increase the understanding of orthostatic intolerance (proneness for fainting), a common clinical problem.

In view of the limited data about autonomic cardiovascular control in relation to mental stress in space, a hypothesis that mental load may alter cardiovascular neural response in microgravity was tested on five (5) crewmembers before, during, and after spaceflight over three 10- to 11-day scientific European Space Agency (ESA)-Soyuz missions (Odissea, Cervantes, and Delta) to the ISS. This investigation examined cardiovascular responses to mental arithmetic tasks and found no effect in space when compared to baseline testing results for heart rate, mean arterial pressure, and Heart Rate Variability (HRV) parameters (Aubert et al. 2009).

Parallel multi-point studies on the same subjects for up to 25 post-flight days found heart rate (HR) increase only with the standing position in early postflight, and researchers concluded this as typical response to upright stress after returning to Earth’s gravity and full tolerance is reestablished after 4 days (Beckers et al. 2009). Symptoms such as dizziness, loss of balance and/or vision, or consciousness from uncompensated fall in blood pressure disappeared rather quickly after flight, but it was unclear how long changes in dynamic HR control need to recover. Verheyden et al. (2007) used a simple paced-breathing method to investigate respiratory control on the autonomic heart rhythms and data collected 10 days prior to launch, then 1 and 25 days upon return to Earth show that in spite of increased HR and associated reduction in the rhythmic fluctuation of heart rate with breathing (technically known as Respiratory Sinus Dysrhythmia or RSD), respiratory-mediated blood pressure dynamics are unchanged following short-duration spaceflight. The results suggest that a fundamental neural control deficit from microgravity deconditioning is less likely, and the post-flight reductions in RSD and blood-pressure control of heart rate are actually appropriate autonomic adjustments that account for the altered blood flow regulation after spaceflight which will typically resolve within 25 days after landing. A comprehensive in-flight study including 6 additional astronauts who took part in six long-duration Increments for up to 6 months on board the ISS. In this study, primary cardiovascular data were measured as a function of body position pre-flight and in microgravity. The main findings are that HR and blood pressure (BP) in microgravity do not change significantly compared to the supine (lying face upward) pre-flight values during these extended stays. However, long-term space missions seem to induce chronic relaxation of the circulation in humans which was nicely demonstrated by one of the subjects having borderline high blood pressure before flight and subsequently showing normal BP in space. One interesting, and unexpected, result is the blood pressure neural feedback linked to controlling heart rate appear to slow significantly in space but the cause(s) is unclear and needs further investigation.

No astronauts in the studies showed symptoms or signs of impending fainting the first days after landing which strongly supports the involvement of effective exercise countermeasures in the adaptation process to prolonged space missions. It is suggested that individual performance on countermeasures should therefore be shared between scientists in the future to improve the depth, scientific outcome, and overall conclusion of these studies (Verheyden et al. 2009, 2010).

NASA Image ISS015E08658 View of Expedition 15 cosmonaut and Flight Engineer (FE-1), Oleg Kotov, collecting medical data for the Cognitive Cardiovascular (Cardiocog-2) Experiment in the Service Module (SM)/Zvezda. He is wearing blood pressure and heart rate measuring devices, including a finger cuff, and a blue vest visible next to him.+ View Larger Image

NASA Image ISS015E08659 Cosmonaut Oleg V. Kotov, Expedition 15 flight engineer, reads the procedure checklist while collecting medical data for the Cognitive Cardiovascular (Cardiocog-2) experiment in the Zvezda Service Module of the International Space Station. Cardiocog-2 will determine the impact of weightlessness on the cardiovascular system and respiratory system and the cognitive reactions of crewmembers. The results of this study will be used to develop additional countermeasures that will continue to keep crewmembers healthy during long-duration space exploration.+ View Larger Image

NASA Image ISS015E08660 Cosmonaut Oleg V. Kotov, Expedition 15 flight engineer, collects medical data for the Cognitive Cardiovascular (Cardiocog-2) experiment in the Zvezda Service Module of the International Space Station. He is wearing blood pressure and heart rate measuring devices, including a finger cuff, and a blue vest visible next to him.+ View Larger Image